On the day for opening the Conclave, a Mass of the Holy Ghost is sung in St. Peter's, a sermon preached, and the Cardinals enter the Vatican in solemn procession. The Veni Creator is sung, and they then take the oath to observe the Apostolic constitutions, after which they go to their cells, which are assigned to them by lot. All the other Conclavists then take oath not to meddle in the election nor reveal any secrets that may come to their knowledge.

Later in the evening the bell rings, and the order, "Extra omnes!"—"all outside"—is given, after which the door is locked by the Camerlengo from within and the Marshal from without. The Camerlengo and three other Cardinals then make a tour of inspection throughout the building to see that everything is in order and that no strangers are present.

The door of the Conclave is that of the Sala Regia, at the top of the Marshal's staircase. All other doors giving access to that part of the Vatican have been previously walled up. Beside this door are four turns, similar to those sometimes seen in the walls of kitchens, through which correspondence and food are passed. One of these turns is closely guarded by bishops, another by prothonotaries, the remaining two being in charge of prelates of the papal tribunals.

The Cardinals are at liberty to receive letters on personal or family matters, but not communications bearing upon the election. To ensure the observance of this rule all correspondence passing through the turns, either from within or without, is read by the guardians, unless it is marked "Private," in which case it goes direct to the Secretary of the Conclave, and is read by the chiefs of orders—certain Cardinals who are responsible for the direction of each day's business—who, if they think fit, may read it to the whole college.

Newspapers and books are admitted without restriction, and a Cardinal may go to the turn to speak to anyone, but only in the presence of its guardians.